static int md_bitmap_read_sb()

in md-bitmap.c [578:733]

• 127 lines of code
• 31 McCabe index (conditional complexity)

static int md_bitmap_read_sb(struct bitmap *bitmap)
{
	char *reason = NULL;
	bitmap_super_t *sb;
	unsigned long chunksize, daemon_sleep, write_behind;
	unsigned long long events;
	int nodes = 0;
	unsigned long sectors_reserved = 0;
	int err = -EINVAL;
	struct page *sb_page;
	loff_t offset = bitmap->mddev->bitmap_info.offset;

	if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
		chunksize = 128 * 1024 * 1024;
		daemon_sleep = 5 * HZ;
		write_behind = 0;
		set_bit(BITMAP_STALE, &bitmap->flags);
		err = 0;
		goto out_no_sb;
	}
	/* page 0 is the superblock, read it... */
	sb_page = alloc_page(GFP_KERNEL);
	if (!sb_page)
		return -ENOMEM;
	bitmap->storage.sb_page = sb_page;

re_read:
	/* If cluster_slot is set, the cluster is setup */
	if (bitmap->cluster_slot >= 0) {
		sector_t bm_blocks = bitmap->mddev->resync_max_sectors;

		bm_blocks = DIV_ROUND_UP_SECTOR_T(bm_blocks,
			   (bitmap->mddev->bitmap_info.chunksize >> 9));
		/* bits to bytes */
		bm_blocks = ((bm_blocks+7) >> 3) + sizeof(bitmap_super_t);
		/* to 4k blocks */
		bm_blocks = DIV_ROUND_UP_SECTOR_T(bm_blocks, 4096);
		offset = bitmap->mddev->bitmap_info.offset + (bitmap->cluster_slot * (bm_blocks << 3));
		pr_debug("%s:%d bm slot: %d offset: %llu\n", __func__, __LINE__,
			bitmap->cluster_slot, offset);
	}

	if (bitmap->storage.file) {
		loff_t isize = i_size_read(bitmap->storage.file->f_mapping->host);
		int bytes = isize > PAGE_SIZE ? PAGE_SIZE : isize;

		err = read_page(bitmap->storage.file, 0,
				bitmap, bytes, sb_page);
	} else {
		err = read_sb_page(bitmap->mddev,
				   offset,
				   sb_page,
				   0, sizeof(bitmap_super_t));
	}
	if (err)
		return err;

	err = -EINVAL;
	sb = kmap_atomic(sb_page);

	chunksize = le32_to_cpu(sb->chunksize);
	daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
	write_behind = le32_to_cpu(sb->write_behind);
	sectors_reserved = le32_to_cpu(sb->sectors_reserved);
	/* Setup nodes/clustername only if bitmap version is
	 * cluster-compatible
	 */
	if (sb->version == cpu_to_le32(BITMAP_MAJOR_CLUSTERED)) {
		nodes = le32_to_cpu(sb->nodes);
		strlcpy(bitmap->mddev->bitmap_info.cluster_name,
				sb->cluster_name, 64);
	}

	/* verify that the bitmap-specific fields are valid */
	if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
		reason = "bad magic";
	else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
		 le32_to_cpu(sb->version) > BITMAP_MAJOR_CLUSTERED)
		reason = "unrecognized superblock version";
	else if (chunksize < 512)
		reason = "bitmap chunksize too small";
	else if (!is_power_of_2(chunksize))
		reason = "bitmap chunksize not a power of 2";
	else if (daemon_sleep < 1 || daemon_sleep > MAX_SCHEDULE_TIMEOUT)
		reason = "daemon sleep period out of range";
	else if (write_behind > COUNTER_MAX)
		reason = "write-behind limit out of range (0 - 16383)";
	if (reason) {
		pr_warn("%s: invalid bitmap file superblock: %s\n",
			bmname(bitmap), reason);
		goto out;
	}

	/* keep the array size field of the bitmap superblock up to date */
	sb->sync_size = cpu_to_le64(bitmap->mddev->resync_max_sectors);

	if (bitmap->mddev->persistent) {
		/*
		 * We have a persistent array superblock, so compare the
		 * bitmap's UUID and event counter to the mddev's
		 */
		if (memcmp(sb->uuid, bitmap->mddev->uuid, 16)) {
			pr_warn("%s: bitmap superblock UUID mismatch\n",
				bmname(bitmap));
			goto out;
		}
		events = le64_to_cpu(sb->events);
		if (!nodes && (events < bitmap->mddev->events)) {
			pr_warn("%s: bitmap file is out of date (%llu < %llu) -- forcing full recovery\n",
				bmname(bitmap), events,
				(unsigned long long) bitmap->mddev->events);
			set_bit(BITMAP_STALE, &bitmap->flags);
		}
	}

	/* assign fields using values from superblock */
	bitmap->flags |= le32_to_cpu(sb->state);
	if (le32_to_cpu(sb->version) == BITMAP_MAJOR_HOSTENDIAN)
		set_bit(BITMAP_HOSTENDIAN, &bitmap->flags);
	bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
	strlcpy(bitmap->mddev->bitmap_info.cluster_name, sb->cluster_name, 64);
	err = 0;

out:
	kunmap_atomic(sb);
	/* Assigning chunksize is required for "re_read" */
	bitmap->mddev->bitmap_info.chunksize = chunksize;
	if (err == 0 && nodes && (bitmap->cluster_slot < 0)) {
		err = md_setup_cluster(bitmap->mddev, nodes);
		if (err) {
			pr_warn("%s: Could not setup cluster service (%d)\n",
				bmname(bitmap), err);
			goto out_no_sb;
		}
		bitmap->cluster_slot = md_cluster_ops->slot_number(bitmap->mddev);
		goto re_read;
	}


out_no_sb:
	if (test_bit(BITMAP_STALE, &bitmap->flags))
		bitmap->events_cleared = bitmap->mddev->events;
	bitmap->mddev->bitmap_info.chunksize = chunksize;
	bitmap->mddev->bitmap_info.daemon_sleep = daemon_sleep;
	bitmap->mddev->bitmap_info.max_write_behind = write_behind;
	bitmap->mddev->bitmap_info.nodes = nodes;
	if (bitmap->mddev->bitmap_info.space == 0 ||
	    bitmap->mddev->bitmap_info.space > sectors_reserved)
		bitmap->mddev->bitmap_info.space = sectors_reserved;
	if (err) {
		md_bitmap_print_sb(bitmap);
		if (bitmap->cluster_slot < 0)
			md_cluster_stop(bitmap->mddev);
	}
	return err;
}